The Collaborative International Dictionary of English v.0.48:

Saliva \Sa*li"va\, n. [L.; cf. Gr. ?.] (Physiol.)
   The secretion from the salivary glands.
   [1913 Webster]

   Note: In man the saliva is a more or less turbid and slighty
         viscid fluid, generally of an alkaline reaction, and is
         secreted by the parotid, submaxillary, and sublingual
         glands. In the mouth the saliva is mixed with the
         secretion from the buccal glands. The secretions from
         the individual salivary glands have their own special
         characteristics, and these are not the same in all
         animals. In man and many animals mixed saliva, i.e.,
         saliva composed of the secretions of all three of the
         salivary glands, is an important digestive fluid on
         account of the presence of the peculiar enzyme,
         ptyalin.
         [1913 Webster]

WordNet (r) 3.0 (2006):

saliva
    n 1: a clear liquid secreted into the mouth by the salivary
         glands and mucous glands of the mouth; moistens the mouth
         and starts the digestion of starches [syn: saliva,
         spit, spittle]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "saliva":
   absorption, assimilation, bile, chyle, colostrum, digestion,
   digestive system, discharge, dribble, drivel, drool, expectoration,
   foam, froth, gastric juice, gastrointestinal tract, gleet, humor,
   ichor, ingestion, intestinal juice, lachryma, lactation,
   leukorrhea, liver, lymph, matter, milk, mouth-watering, mucor,
   mucus, pancreas, pancreatic digestion, pancreatic juice,
   peccant humor, phlegm, predigestion, ptyalism, purulence, pus,
   rheum, salivary digestion, salivary glands, salivation, sanies,
   secondary digestion, serous fluid, serum, sialagogue, slabber,
   slaver, slobber, snot, spit, spittle, sputum, suppuration, sweat,
   tear, teardrop, the whites, urine, water